tomcat wont start up on linux machine

I'm new to Linux but having spent a whole day I Installed Java and Tomcat. My goal is to host an App with this Linux box. I know it all works fine from my windows based machine, but it is my laptop so I'm planning to use the Linux Box as my dedicated server.

Following many many forums I've now got Tomcat 7 installed. However i cannot get it to start.

Changing to the tomcat directory and "./startup.sh" i get the following output:

Using CATALINA_BASE: /usr/local/tomcat
Using CATALINA_HOME: /usr/local/tomcat
Using CATALINA_TMPDIR: /usr/local/tomcat/temp
Using JRE_HOME: usr/lib/jvm/java-6-sun/
Using CLASSPATH: /usr/local/tomcat/bin/bootstrap.jar:/usr/local/tomcat/bin/tomcat-juli.jar

That's the end of the output.

However localhost:8080 is not up, and in the tomcat log file is the error "eval: 1: usr/lib/jvm/java-6-sun//bin/java: not found"

Hopefully there is some expert here who can help me with this problem. Please note that I'm a novice when it comes to Linux.